Extract data from nvarchar column

The case: 

We have a log table that include Message column (nvarchar).

We need to extract from the message some data, for example: Entity ID and Entity Type.

SELECT LogId,

(case when CHARINDEX ('EntityID:', Msg) > 0

then substring ( Msg, 

CHARINDEX ('EntityID:', Msg) + 9, -- 9=length of 'EntityID:'

( case when CHARINDEX ('EntityID:', Msg) > 0 

then ( CHARINDEX (',', Msg, CHARINDEX ('EntityID:', Msg)) 

- CHARINDEX ('EntityID:', Msg) - 9) -- 9=length of 'EntityID:'

else CHARINDEX ('EntityID:', Msg) + 9 -- 9=length of 'EntityID:'

end

)

)

else NULL

end ) as EntityID,

(case when CHARINDEX ('EntityType:', Msg) > 0

then substring ( Msg, 

CHARINDEX ('EntityType:', Msg) + 11, -- 11=length of 'EntityID:'

( case when CHARINDEX ('EntityType:', Msg) > 0 

then ( CHARINDEX (',', Msg, CHARINDEX ('EntityType:', Msg)) 

- CHARINDEX ('EntityType:', Msg) - 11) -- 11=length of 'EntityID:'

else CHARINDEX ('EntityType:', Msg) + 11 -- 11=length of 'EntityID:'

end

)

)

else NULL

end ) as EntityType

FROM OurLogTable